The Effect of Tethered Cord Release on Coronal Spinal Balance in Tight Filum Terminale

Study Design. A retrospective review of coronal spine balance after tethered cord release for children with tight filum terminale. Objective. To understand the effects of untethering on coronal spine balance for these patients. Summary of Background Data. In patients with tight filum terminale, the spinal cord is tethered by a thickened filum with a low conus medullaris but without other forms of spinal dysraphism. There have not been studies examining the effects of spinal cord untethering on coronal spinal alignment in children with tight filum terminale. Methods. Forty-five consecutive pediatric patients with tight filum terminale who had undergone untethering were evaluated. Their presenting signs and symptoms, pre- and postsurgery imagings, and clinical courses were reviewed for scoliosis progression. Results. Twenty-six girls and 19 boys underwent tethered cord release at a mean age of 4.5 years. The prevalence of coronal spinal malalignment, manifesting as scoliosis, before the untethering procedure was 31% (14 of 45). During the follow-up period, nine patients had coronal spinal alignment that worsened >10 degrees (five patients eventually underwent surgical fusion), two patients had spinal alignment that improved, and five patients' curves stabilized after untethering surgery. Therefore, at the end of the follow-up period, 9 of 45 patients (20%) had worsened coronal spinal alignment. In the multivariate analysis, patients who presented with a Cobb angle greater than 35 were most likely to progress (P = 0.002, odds ratio = 21). There was no operative morbidity or mortality associated with scoliosis surgery. Conclusion. A significant number of children with tight filum terminale were found to present with scoliosis. In patients with less severe curves, tethered cord release may halt scoliosis progression.